The security of enclosures accessible by way of doors has been the subject of many forms of latch and lock contrivances. Latches accessible only from within the served enclosure include key-served tumbler locks, dead bolts, slotted latches, and links such as chains, just to name a few. Tumbler locks and the usual dead bolts lose their security feature when actuated to open the door a small amount. Occasionally there is a need to allow a slight opening of a door without totally losing control of the access limitation a small opening provides such as in hotels and motels where room cleaning services are often provided with a passkey. Normally the short chains, secured to the doorframe and fastened to the door with screws, serve quite well. However, unauthorized entry is often gained through the use of bolt cutters extended through the slightly opened door, thereby readily cutting the chains. Slotted ridged latches and chains are both only as strong as the fasteners by which they are attached. Therefore, extreme force is often used to break such latches or simply dismount them. Most such latches are made from light weight stamped plate, such as may be seen in U.S. Pat. Nos., 5,531,490, 646,810, 6,354,32 1,799,265, and 1,388,712, and are mounted, in most cases, in a manner whereby the shot bolt receiver is located on the door frame adjacent the door and the latch bolt is fastened to the door, thus exposing the bolt to potential shearing by an intruder. When such sliding bolt latches are used as security latches for personnel entrance or access doors they are generally mounted with light screws secured to the door facing and the door itself. Generally speaking, the slide bolt latch is the only defense the occupant has when partially opening the door. It should be essential that the allowable opening be kept to an absolute minimum and that the elements of the slide bolt latch be of sufficient strength to resist extreme force and still be able to maintain a substantial purchase on the mounting surface. The wider the door is allowed to open when latched, the more adverse strain may be applied.
Mounting such light weight latches, such as those cited above, to the door and door facing have proven to be insufficient for security purposes due to poor construction, light weight materials, and insufficient depth of the screws to penetrate the facing and reach into the wall framing located behind the facing. Such slide bolt door latches are quite well known for their ability to pinch fingers when attempting to release the latch for opening the door. In addition these latches tend to hang on the door when not in use and cause damage to the door or door casing, especially in the case of the 1,388,712 patent cited above.
More recently it has become mandatory in some apartment building, hotels, motels, and the like to provide some means of over-riding the internal latch apparatus to allow emergency access in cases where the occupant has actuated both the door's dead bolt and the internal security latch. The use of a passkey for the dead bolt lock is ineffective in such cases. Therefore, unauthorized tactics must be employed to gain entry to disabled occupants in situations where time is critical. Such entry over-riding tactics are often very destructive, time consuming, and very disturbing to adjacent occupants. Obviously, if such tactics can be avoided lives may be saved and property destruction can be reduced. It is therefore an object of the invention disclosed herein to provide a security bolt latch for the limited opening of doors that includes a way to physically release the latch assembly in an emergency by authorized personnel without damage to the door or wall framing with a minimal disturbance to adjacent occupants.